Effect of juglone from Juglans mandshurica bark on the activity of wood decay fungi

Juglone was extracted from Juglans mandshurica bark via vacuum-assisted steam stripping. The extract was characterized by Fourier transform infrared spectroscopy (FTIR), H-1 nuclear magnetic resonance (NMR), and gas chromatography/mass spectrometry (GC-MS). The extraction process was easy to perform and produced excellent yields (0.22 g juglone/100 g of bark) of a high purity extract (96.42% juglone). The yield was much higher than that of previous studies. The biological activity of the extract was assessed in vitro against Aspergillus niger, Paecilomyces variotii, Trametes versicolor, Gloeophyllum trabeum, Postia placenta, and Chaetomium globosum. Juglone showed good antifungal activity with the first four fungi listed, even at concentrations as low as 500 ppm; poor activity was shown with the last two fungi listed. The results suggest that juglone has promise as a natural wood protectant; further studies are planned.